In the cutting of profile stock, most typically L-section angle iron, it is necessary to attack the material in a direction not parallel to either of the flanges of the angle iron. The standard shear comprises, however, a vertically moving blade plate that carries a movable blade and that is sandwiched between two massive upright frame plates carrying a fixed blade. Typically the frame plates are formed with one or more throughgoing ports through which material is engaged to cut it. In the simplest such arrangement as shown in German patent 2,838,733, angle iron is positioned in the shear with its two flanges diverging oppositely upward and is then cut with the vertically moving blade.
Such an arrangement does not fit into standard production lines, because in such lines the angle iron is invariably sitting with one of its flanges horizontal and the other vertical. To avoid having to tip the workpiece to cut it, an arrangement is suggested in U.S. Pat. No. 2,728,391 wherein the profile-cutting blade is carried on a secondary or angle blade slide that moves in the frame at an angle of about 45.degree. to the vertical.
To this end the front frame plate is formed with a window having edges extending at the 45.degree. angle and forming guide surfaces for the angle blade slide. Force is transmitted from the working slide to the angle slide by a bar projecting from the working slide and cooperating with a pin projecting from the working slide which pulls back the angle slide when the working slide is lifted after a cut. The angle slide thus does not lie in the same plane as the working slide but in a plane between that of the working slide and that of the front frame plate. The position of the movable blade relative to the stationary blade is established by the working slide. The angle slide is held against the front frame plate by the working slide.
Considerable force must be transmitted via the guide surfaces formed in the front plate. This element is typically made of a steel that has poor wear properties, so that problems are frequently encountered with the angle slide. In addition the force transmission from the working-slide plane to the angle-slide plane creates transverse stresses in the frame that serve no useful function and that, in fact, can lead to damage of the shear. Accordingly these plates must be massive to withstand these transverse forces.